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<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2011 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: OutputStreamWriter.html 926 2014-09-17 03:05:56Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.dellroad.stuff.io;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>import java.io.FilterOutputStream;<a name="line.10"></a>
<span class="sourceLineNo">011</span>import java.io.IOException;<a name="line.11"></a>
<span class="sourceLineNo">012</span>import java.io.OutputStream;<a name="line.12"></a>
<span class="sourceLineNo">013</span><a name="line.13"></a>
<span class="sourceLineNo">014</span>/**<a name="line.14"></a>
<span class="sourceLineNo">015</span> * Serializes zero or more {@link OutputStream}s inside a single underlying {@link OutputStream}. The results can be<a name="line.15"></a>
<span class="sourceLineNo">016</span> * deserialized as equally many distinct {@link java.io.InputStream}s on the other end using an {@link InputStreamReader}.<a name="line.16"></a>
<span class="sourceLineNo">017</span> * Each {@link OutputStream} may contain an arbitrary amount of data.<a name="line.17"></a>
<span class="sourceLineNo">018</span> *<a name="line.18"></a>
<span class="sourceLineNo">019</span> * &lt;p&gt;<a name="line.19"></a>
<span class="sourceLineNo">020</span> * To use this class, invoke {@link #start} to start a new {@link OutputStream}, write to it by writing to this<a name="line.20"></a>
<span class="sourceLineNo">021</span> * class normally, and then use {@link #stop} to close the current {@link OutputStream}. A new, subsequent {@link OutputStream}<a name="line.21"></a>
<span class="sourceLineNo">022</span> * is created by invoking {@link #start} again.<a name="line.22"></a>
<span class="sourceLineNo">023</span> * &lt;/p&gt;<a name="line.23"></a>
<span class="sourceLineNo">024</span> *<a name="line.24"></a>
<span class="sourceLineNo">025</span> * &lt;p&gt;<a name="line.25"></a>
<span class="sourceLineNo">026</span> * Each {@link OutputStream} written in this way will be read as distinct {@link java.io.InputStream} by the<a name="line.26"></a>
<span class="sourceLineNo">027</span> * {@link InputStreamReader} at the other end.<a name="line.27"></a>
<span class="sourceLineNo">028</span> * &lt;/p&gt;<a name="line.28"></a>
<span class="sourceLineNo">029</span> *<a name="line.29"></a>
<span class="sourceLineNo">030</span> * &lt;p&gt;<a name="line.30"></a>
<span class="sourceLineNo">031</span> * Instances of this class are thread safe.<a name="line.31"></a>
<span class="sourceLineNo">032</span> * &lt;/p&gt;<a name="line.32"></a>
<span class="sourceLineNo">033</span> *<a name="line.33"></a>
<span class="sourceLineNo">034</span> * @see InputStreamReader<a name="line.34"></a>
<span class="sourceLineNo">035</span> */<a name="line.35"></a>
<span class="sourceLineNo">036</span>public class OutputStreamWriter extends FilterOutputStream {<a name="line.36"></a>
<span class="sourceLineNo">037</span><a name="line.37"></a>
<span class="sourceLineNo">038</span>    private final RandomEscape randomEscape = new RandomEscape();<a name="line.38"></a>
<span class="sourceLineNo">039</span><a name="line.39"></a>
<span class="sourceLineNo">040</span>    private int escape;<a name="line.40"></a>
<span class="sourceLineNo">041</span>    private boolean started;<a name="line.41"></a>
<span class="sourceLineNo">042</span>    private boolean closed;<a name="line.42"></a>
<span class="sourceLineNo">043</span><a name="line.43"></a>
<span class="sourceLineNo">044</span>    /**<a name="line.44"></a>
<span class="sourceLineNo">045</span>     * Constructor.<a name="line.45"></a>
<span class="sourceLineNo">046</span>     *<a name="line.46"></a>
<span class="sourceLineNo">047</span>     * @param output the underlying {@link OutputStream} that will carry nested {@link OutputStream}s within it<a name="line.47"></a>
<span class="sourceLineNo">048</span>     */<a name="line.48"></a>
<span class="sourceLineNo">049</span>    public OutputStreamWriter(OutputStream output) {<a name="line.49"></a>
<span class="sourceLineNo">050</span>        super(output);<a name="line.50"></a>
<span class="sourceLineNo">051</span>        this.escape = this.randomEscape.next();<a name="line.51"></a>
<span class="sourceLineNo">052</span>    }<a name="line.52"></a>
<span class="sourceLineNo">053</span><a name="line.53"></a>
<span class="sourceLineNo">054</span>    /**<a name="line.54"></a>
<span class="sourceLineNo">055</span>     * Start a new {@link OutputStream}.<a name="line.55"></a>
<span class="sourceLineNo">056</span>     *<a name="line.56"></a>
<span class="sourceLineNo">057</span>     * @throws IOException if this instance is closed<a name="line.57"></a>
<span class="sourceLineNo">058</span>     * @throws IOException if an {@link OutputStream} is already started<a name="line.58"></a>
<span class="sourceLineNo">059</span>     */<a name="line.59"></a>
<span class="sourceLineNo">060</span>    public synchronized void start() throws IOException {<a name="line.60"></a>
<span class="sourceLineNo">061</span>        if (this.closed)<a name="line.61"></a>
<span class="sourceLineNo">062</span>            throw new IOException("this instance is closed");<a name="line.62"></a>
<span class="sourceLineNo">063</span>        if (this.started)<a name="line.63"></a>
<span class="sourceLineNo">064</span>            throw new IOException("already started");<a name="line.64"></a>
<span class="sourceLineNo">065</span>        this.started = true;<a name="line.65"></a>
<span class="sourceLineNo">066</span>    }<a name="line.66"></a>
<span class="sourceLineNo">067</span><a name="line.67"></a>
<span class="sourceLineNo">068</span>    /**<a name="line.68"></a>
<span class="sourceLineNo">069</span>     * End the current {@link OutputStream}. This flushes the underlying output.<a name="line.69"></a>
<span class="sourceLineNo">070</span>     * A new {@link OutputStream} will be created upon the next invocation of {@link #start}.<a name="line.70"></a>
<span class="sourceLineNo">071</span>     *<a name="line.71"></a>
<span class="sourceLineNo">072</span>     * @throws IOException if this instance is closed<a name="line.72"></a>
<span class="sourceLineNo">073</span>     * @throws IOException if no {@link OutputStream} is currently started<a name="line.73"></a>
<span class="sourceLineNo">074</span>     * @throws IOException if the underlying {@link OutputStream} throws an exception<a name="line.74"></a>
<span class="sourceLineNo">075</span>     */<a name="line.75"></a>
<span class="sourceLineNo">076</span>    public synchronized void stop() throws IOException {<a name="line.76"></a>
<span class="sourceLineNo">077</span>        if (this.closed)<a name="line.77"></a>
<span class="sourceLineNo">078</span>            throw new IOException("this instance is closed");<a name="line.78"></a>
<span class="sourceLineNo">079</span>        if (!this.started)<a name="line.79"></a>
<span class="sourceLineNo">080</span>            throw new IOException("not started");<a name="line.80"></a>
<span class="sourceLineNo">081</span>        this.started = false;<a name="line.81"></a>
<span class="sourceLineNo">082</span>        this.writeControl(InputStreamReader.CONTROL_SEPARATOR);<a name="line.82"></a>
<span class="sourceLineNo">083</span>        this.flush();<a name="line.83"></a>
<span class="sourceLineNo">084</span>    }<a name="line.84"></a>
<span class="sourceLineNo">085</span><a name="line.85"></a>
<span class="sourceLineNo">086</span>    /**<a name="line.86"></a>
<span class="sourceLineNo">087</span>     * Close this instance. Does nothing if already closed.<a name="line.87"></a>
<span class="sourceLineNo">088</span>     * If there an {@link OutputStream} is already started when this method is invoked, it will be implicitly<a name="line.88"></a>
<span class="sourceLineNo">089</span>     * {@linkplain #stop stopped}.<a name="line.89"></a>
<span class="sourceLineNo">090</span>     *<a name="line.90"></a>
<span class="sourceLineNo">091</span>     * &lt;p&gt;<a name="line.91"></a>
<span class="sourceLineNo">092</span>     * This ends the current {@link OutputStream} and closes the underlying output.<a name="line.92"></a>
<span class="sourceLineNo">093</span>     * &lt;/p&gt;<a name="line.93"></a>
<span class="sourceLineNo">094</span>     *<a name="line.94"></a>
<span class="sourceLineNo">095</span>     * @throws IOException if an there is an error closing the underlying {@link OutputStream}<a name="line.95"></a>
<span class="sourceLineNo">096</span>     */<a name="line.96"></a>
<span class="sourceLineNo">097</span>    @Override<a name="line.97"></a>
<span class="sourceLineNo">098</span>    public synchronized void close() throws IOException {<a name="line.98"></a>
<span class="sourceLineNo">099</span>        if (this.closed)<a name="line.99"></a>
<span class="sourceLineNo">100</span>            return;<a name="line.100"></a>
<span class="sourceLineNo">101</span>        if (this.started) {<a name="line.101"></a>
<span class="sourceLineNo">102</span>            this.started = false;<a name="line.102"></a>
<span class="sourceLineNo">103</span>            this.writeControl(InputStreamReader.CONTROL_SEPARATOR);<a name="line.103"></a>
<span class="sourceLineNo">104</span>        }<a name="line.104"></a>
<span class="sourceLineNo">105</span>        this.closed = true;<a name="line.105"></a>
<span class="sourceLineNo">106</span>        this.out.close();<a name="line.106"></a>
<span class="sourceLineNo">107</span>    }<a name="line.107"></a>
<span class="sourceLineNo">108</span><a name="line.108"></a>
<span class="sourceLineNo">109</span>    @Override<a name="line.109"></a>
<span class="sourceLineNo">110</span>    public synchronized void write(int ch) throws IOException {<a name="line.110"></a>
<span class="sourceLineNo">111</span>        if (this.closed)<a name="line.111"></a>
<span class="sourceLineNo">112</span>            throw new IOException("this instance is closed");<a name="line.112"></a>
<span class="sourceLineNo">113</span>        if (!this.started)<a name="line.113"></a>
<span class="sourceLineNo">114</span>            this.started = true;<a name="line.114"></a>
<span class="sourceLineNo">115</span>        if ((ch &amp; 0xff) == this.escape) {<a name="line.115"></a>
<span class="sourceLineNo">116</span>            this.writeControl(InputStreamReader.CONTROL_ESCAPE);<a name="line.116"></a>
<span class="sourceLineNo">117</span>            return;<a name="line.117"></a>
<span class="sourceLineNo">118</span>        }<a name="line.118"></a>
<span class="sourceLineNo">119</span>        this.out.write(ch);<a name="line.119"></a>
<span class="sourceLineNo">120</span>    }<a name="line.120"></a>
<span class="sourceLineNo">121</span><a name="line.121"></a>
<span class="sourceLineNo">122</span>    private synchronized void writeControl(int control) throws IOException {<a name="line.122"></a>
<span class="sourceLineNo">123</span>        this.out.write(this.escape);<a name="line.123"></a>
<span class="sourceLineNo">124</span>        this.out.write(this.escape ^ control);<a name="line.124"></a>
<span class="sourceLineNo">125</span>        this.escape = this.randomEscape.next();<a name="line.125"></a>
<span class="sourceLineNo">126</span>    }<a name="line.126"></a>
<span class="sourceLineNo">127</span>}<a name="line.127"></a>
<span class="sourceLineNo">128</span><a name="line.128"></a>




























































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